1. Field of the Invention
The present invention relates to a fuel injection device for injecting fuel into an internal combustion engine. In particular, the present invention relates to a technology of correcting variation in an injector.
2. Description of Related Art
There is an injector attached with a code table, which stores injector individual data based on an injection rate of the injector measured outside a cylinder of an engine when the injector is shipped. For example, injection start delay Td, injection end delay Te and several injection amounts Q are measured outside the cylinder of the engine when the injector is shipped. Then, variations from designed median values are converted into energization periods or the like and are stored in the code table such as a QR code. The code table is attached to the injector.
A vehicle, in which the injector is mounted, reads the injector individual data of the injector from the code table attached to the injector and stores the injector individual data into a controller. The controller has a correcting device for performing variation correction of the injector based on the stored injector individual data. The correcting device corrects a control parameter corresponding to an engine operation state based on the injector individual data to bring injection characteristics of the injector to the designed median values, more specifically, to the designed median values give or take appropriate variations (for example, as described in JP-A-2003-227393).
In recent years, in order to simultaneously achieve reduction of engine vibration and engine noise, purification of exhaust gas and improvement of engine output and fuel consumption at high levels, highly accurate injection control has been required. Specifically, extremely accurate injection control is required for multi-injection performing multiple fuel injections during one cycle. Therefore, the variation correction is performed to correct the injection variation of the injector. However, it has been difficult to obtain the accurate injection characteristics substantially conforming to the deigned median values in a state in which the injector is actually mounted in the engine.
The inventor discovered that tendency of the variation differs between an outside and an inside of the cylinder. That is, the correction becomes excessive inside the cylinder due to in-cylinder pressure Pcyl if a variation correction value is calculated directly from the injector individual data obtained outside the cylinder. In such a case, there is a possibility that the injection characteristics deviate from the designed median values.